16-Bit Fully Isolated Voltage Output Module Using the AD5662 DAC, ADuM1401 Digital Isolator, and External Amplifiers
Figure 1. 16-Bit Isolated Industrial Control Voltage Output Module (Simplified Schematic)
The ADR02 was chosen as the reference for this circuit. The ADR02 has excellent ppm drift specs at 9 ppm/°C max. It is also often used in industrial applications due to its high input range to 36 V.
The ADuM1401 is a four-channel digital isolator based on Analog Devices iCoupler® technology. It is used to provide isolation between the AD5662 and the system microcontroller, with an isolation rating of 2.5 kV rms. Three wires are used to connect the standard SPI interface connections to the AD5662: SYNC, SCLK, and DIN.
Figure 2 shows an output error plot (integral nonlinearity) of the output of the circuit when the AD5662 is used with the ADR02 external reference. Results are shown in %FSR (full-scale range) as a function of input code.
|AD5662||2.7-5.5V, 16-Bit nanoDAC® Converter in a Sot-23||
|ADR02||Ultracompact, Precision 5.0 V Voltage Reference||
|OP2177||Precision Low Noise, Low Input Bias Current Dual Op Amp||
|ADUM1401||Quad-Channel Digital Isolator (3/1 Channel Directionality)||